1. Field of the Invention
The present invention relates to a solid-state imaging device, a method for controlling a solid-state imaging device, and an imaging device.
Priority is claimed on Japanese Patent Application No. 2012-114446, filed May 18, 2012, the content of which is incorporated herein by reference.
2. Description of Related Art
In recent years, CMOS (Complementary Metal Oxide Semiconductor)-type solid-state imaging devices (hereinafter, referred to as “MOS-type solid-state imaging devices”) have attracted attention as a solid-state imaging device and have been put to practical use.
Such MOS-type solid-state imaging device can be driven with a single power supply unlike CM (Charge Coupled Device)-type solid-state imaging devices. In addition, a CCD-type solid-state imaging device requires dedicated manufacturing processes, whereas the MOS-type solid-state imaging device can be manufactured using the same manufacturing processes as those of other LSIs. For this reason, the MOS-type solid-state imaging device easily deals with an SOC (System On Chip), and can realize the multi-functionalization of the solid-state imaging device.
In addition, the MOS-type solid-state imaging device includes an amplifying circuit in each pixel and thus amplifies signal charges within the pixel. For this reason, the MOS-type solid-state imaging device has a configuration which is hardly influenced by noise from a signal transmission path. Further, the MOS-type solid-state imaging device is characterized in that the signal charge of each pixel can be selected and extracted (selection scheme), and the accumulation time or the reading order of signals can be freely controlled for each pixel in principle.
Previously, as exposure types of general MOS-type solid-state imaging devices (hereinafter, also referred to as a “solid-state imaging devices”), a line exposure type and a global exposure type have been known. In the line exposure type, a large number of pixels arrayed two-dimensionally within the solid-state imaging device are exposed at a timing which is different for each row. The line exposure type is a type in which a video signal of a subject is obtained by sequentially reading signal charges generated after performing exposure of a row of a certain unit by the photoelectric conversion element within pixels in the row. In the case of the line exposure type, exposure and reading can be continuously performed in row units. For this reason, it is possible to obtain a video signal of a subject in a state in which the influence of noise generated in an accumulation section that accumulates the signal charge generated by the photoelectric conversion element is suppressed to a minimum. However, when an image of a moving subject is captured in the line exposure type, an image of the subject cannot be correctly captured due to the exposure timing different for each row. Particularly in the line exposure type, there is a problem that the distorted video of the subject is obtained depending on the direction in which the subject moves.
On the other hand, the global exposure type is a type in which all the pixels arrayed two-dimensionally within the solid-state imaging device are exposed at a synchronous timing. In the case of the global exposure type, since all the pixels are exposed at a synchronous timing, there is no problem in that a distorted video is obtained even at the time of capturing an image of the moving subject. However, in the global exposure type, since the signal charge generated by the photoelectric conversion element within the pixel is sequentially read after all of the pixels are exposed, it is difficult to suppress the influence of noise generated in the accumulation unit in the pixels that require a long time until the reading of the signal charge is started after terminating exposure. For this reason, in the global exposure-type solid-state imaging device, a video signal having a large amount of noise is obtained more often than in the line exposure-type solid-state imaging device.
In the global exposure-type solid-state imaging device, a circuit for suppressing the influence of noise generated in the accumulation unit as mentioned above is added to the solid-state imaging device, thereby allowing a video signal to be obtained in which the influence of noise is suppressed to a minimum even in the solid-state imaging device in which the global exposure type is adopted. However, the addition of the circuit which suppresses the influence of noise to the solid-state imaging devise causes problems that the total area of the solid-state imaging devise becomes enlarged and the solid-state imaging devise itself becomes enlarged.
As a technique for solving such problems, for example, Japanese Unexamined Patent Application, First Publication No. 2006-49361 discloses a method of which creating a pixel circuit unit of a MOS-type solid-state imaging device as a pixel circuit chip, whereas creating a signal processing unit as a signal processing chip, and superimposing the chips which are separately created. In the art disclosed in Japanese Unexamined Patent Application, First Publication No. 200649361, the pixel circuit chip and the signal processing chip which are separately created are connected to each other through a bump.
On the other hand, if a picture in a dark place, or a picture of a subject having low illuminance, for example, is taken by the MOS-type solid-state imaging device, the long-time exposure may be performed in order to supply sufficient light quantity to the MOS-type solid-state imaging device. However, if the long-time exposure is performed, the temperature of the MOS-type solid-state imaging device increases, thus, the image deteriorates due to the influence of pixel defects caused by dark currents. Therefore, the correction of the pixel detects caused by dark currents is performed by an image processing later.
Moreover, in the MOS-type solid-state imaging device which includes the chips pasted together as disclosed in Japanese Unexamined Patent Application. First Publication No. 2006-49361, it is often the case that a substrate including photoelectric conversion units (pixel circuit chips) is a backside illumination (BSI) type. Since the substrate including the photoelectric conversion units is the backside illumination type, it is possible to supply a lot of light quantity to the photoelectric conversion units. However, in the backside illumination type, the crosstalk of the charges is large due to its configuration. Therefore, in the MOS-type solid-state image sensor of the backside illumination type, if pixel defects caused by dark currents exist, the defects are enlarged by leaking the charges of the pixel defects to the surrounding pixels in the long-time exposure. and it resulted in the large detects. Since it is difficult to correct these large defects by the image processing later, there is a problem of an increase in image degradation.